Topographer&#39;s rule



May 4 1926.

F. M. GARNETT roroGRAPHERs RULE Filed Feb. 6 1925 rig/W dumm 1' 1 showsin Patented May 4 192 6. W v

UNITED STATES 1,583,138 PATENT OFFICE;

, FRED HELL GARRETT, O1 SAVANNAH, GEORGIA.

TOPOGRAPHERS RULE.

Application filed Iebi'uary e, 1925. Serial No. 7,883.

To all whom'z't may concern:

Be it known that I, FRED M. GARNETT, a citizen of the United States,residing at Savannah, in the county of Chatham and State of Georgia,have invented a new and useful Topographers Rule, of which the folvingis a specification.

This invention aims to provide a .simple means whereby a topographer,working anywhere, but more especially in the field, may drawconventional signs rapidly, without shifting to any great extent, thescale whereby the distance from the transit to the object to be plattedis laid off. I

It is within the province of the disclosure to .improve generally and toenhance the utility of devices of that sort to which the inventionappertains;

Althou h a preferred form of the inven-* tion has en shown, it will beunderstood that an instrument maker, working within the scope of what isclaimed, may make such changes as his skill may suggest,-withoutdeparting from the spirit of the invention. i

In the accompanying drawings:-Figure lan a device constructed inaccordance with the invention; Figure 2 is a. cross section on the line22 of Figure 1;

Figure 3 is a fragmentallongitudinal section; Figures 4, 5-and 6 areviews illustrating some of the conventional signs 'which may be drawnbymeans of the instrument forming the subject matter of this application.

In carrying out the invention, there is provided astrip 1, made of anysuitable material and provided along one edge with a scale 2, the strip1 being beveled, if desired, as shown at 3, to that edge whereon thescale 2 is located. The strip 1 is provided at one end with a. hole 4,whereby the strip maybe suspended when not in use. The opening'4 is LOTthe purpose-of attaching the rule to the topog'raphers coat or vest,whilst the rule is being used in the field. The rule, therefore, is notlikely to be lost, as would be the case if it were ept in the pocket orcarried in a note book. B

. suspending the rule with a string, it wil be available at all timesfor instant use, and

will not have to be put into the pocket.

The strip'1is provided with a plurality of opening's, so shaped thatwhen a pencil is moved about the edges of the openings,conventional-signs will be formed. Having this consideration in' mind,the'strlp 1 has a rectangular opening 5, adapted to be used inthedrawing ofthe sign representing a railroad station or pavilion.Rectangular openings 6, 7 and 8, of different sizes, are provided, andthe same are used for drawmg signs representing houses. An irregularrectangu ar opening9 is used for making the sign of a house ofcorresponding shape. The triangular opening 10 shown Figure 1 is usefulfor many purposes, for 4 instance, for indicating a triangulation point.The strip has a circular openingll surrounded by a concentric slot 12.These elements sometimes are. used in the representation of a hub ortransit point. The numeral 14 marks a rectangular opening provided atits corners with diverging restricted slots 15. This opening, or asimilar opening 17, are resorted to in the drawing of the sign 16 forabridge. A circular opening 18 having diametrically opposite slottedextensions 19 forms the sign for a telegraph pole. An arrow-shapedopening 20 produces the sign 21, indicating direc tion. The arcuateopening.31 is employed for 'indicatin curves of any kind, for instance ma highway. Arcu'ate slots 22 and 23, on difl'erent radii, have a utilitywhich will be understood readily by those skilled in the art. l

The strip 1 is supplied with parallel slots a parabola or cycloid, so asto present thinned edges 30. It is clear that-when the pencil, showndiagrammatically in Figure.

3, is drawn along one of the slots 24, or along the slot 26, the pencilwill ride up easily upon the br1dges'27, owing-to the fact that thebr'dges have thinned edges 30,

' spaces being formed between the dashes in e sign 25 shown in Figure 4.Because the maximum height of each bridge 27 is less than thedepth ofthe slot, the pencil cannot jump out of the slot, as the pencil isdrawnalong.

The device is made of a transparent substance. The trans arency of therule enables the topograp erto sketch in the figures in their relativepositions, since the center line of the survey is shown in the note bookin red, all figures and approximate distances being referred to thisline. Since it is possible for the topographer to see through the rule,the conventional signs may be oriented properly with. respect to thecenter line of the survey. It is suggested that the rule may be made outof xylonite or celluloid.

Having thus described the invention, what is claimed is A topographersrulesupplied with a slit, the rule being provided with spaced bridgesextended across the slit, the height of the bridges being appreciablyless than onehalf the thickness of the rule, the bridges havingoppositely disposed thinned edges which coincide with the lower surface,of the rule, the upper surface of each bridge being continuouslyconvexed from one of said thinned edges to the other, the slit beingnarrow enough to constrain a stylus "to right-line movement.

In testimony that I claim the foregoing as my own, I have hereto aflixedmy signature.

FRED MELL GARNETT.

